Process of producing 2-chlor-isopentane.



UNITED STATES PATENT .oFFIo OTTO GBAUL, OF LUDWIGSHAFEN-ON-THE-RHINE, GERMANY ASSIGNOR TO BADISCHE ANILIN & SODA FABBIK, OF LUDWIGSHAFEN-ON-THE-RHIN E, GERMANY, A COR- This invention consists of a process by which an excellent yield of 2-chlor-isopentane and thereby of isoprene can be obtained from a mixture of petrol hydrocarbons, which consists'chiefiy of normal pentane and iscpentane, each of the isomeric pentanes being converted into 2-chlor-isopentane.

According to this invention the hydrocarbon mixture is first treated with chlorin, sothat, for the greater part, monochlorin derivatives are produced, and then these monochlorin derivatives are separated by distillation from more highly chlorinated products and from unaltered hydrocarbons. In this way a mixture is obtained which consists practically of five diflerent monochlorpentanes, namelyn cncncrcrn orn 1v CHaCHaCHi-CHaCHaCl v cn cnmciiacncrcfl a,

* and possibly also contains small quantities Should any tetramethyl-methane be present in the initial material, this gives rise in the first place to monochlor-pentane of the formula- 8 CH and this, upon distillation, is converted into 2-chlor-isopent'ane (formula I). The mixture of monochlorin derivatives is then treated with a reagent capable of splitting ofi halogen hydrid, whereupon a mixture is PORATION.

1,202,282, Specification of Letters Patent.

No Drawing.

PROCESS OF PRODUCING Z-CHLOR-IS OPENTAN'E.

Patented Oct. 24,, 1916.

( Application filed March 13, 1913. Serial No. 754,146.

obtained which consists chiefly of trimethyh ethylene 0 (VIII) 0 \C=CH.CH3

and the three other amylenes possibly in admixture with tane again removed. If necessary,the hydrocarbon residue can be repeatedly subjected to the aforesaid operations. The total quantity of the olefins obtained from the original hydrocarbons is thus converted into pure 2 chlor isopentane, which can further be converted into dichlor-isopentane and into isoprene.

'The following example will serve to illustrate further the nature of my invention,

which, however, is not confined to this example.

Example 13 Boil that fraction of a light petroleum. which boils at temperatures up to about 40 or 45 C. in an enameled vessel provided with a fractionating column, and mix the vapors, after passing through the column, with chlorin, preferably in such a manner that the paraflin vapor is present in excess, and then subject the mixture to the action'of light which is rich in chemically active rays, such for instance as sunlight, or subject them to the action of silent electric discharges, whereupon chlorination at once takes place. The chlorination product and any unaltered hydrocarbon are then condensed and the liquid automatically led back into the boiling vessel, while the hydrochloric acid formed is led away in any suitable manner. The fractionating column is maintained at such a temperature that the chlorinated product is condensed and returned to the vessel, while the unchlorinated product passes through and can be subjected to the action of chlorin. The product in the boiling vessel gradually grows richer in the chlorinated product and the boiling point of the liquid continually rises, and as soon as the boiling point reaches between 75 and 80 0., the chlorination is stopped and the reaction product is subjected to fractional distillation. That part which boils at from 75 to 105 C.

is vaporized and the vapor is passed over two to three times its Weight of powdered quicklime at from 375 to 450 C. The olefin produced is then stirred well for from 4 to 6 hours with three times its weight of-concentrated aqueous hydrochloric acid, and any unaltered olefin is thereupon'distilled away from the tertiary isoamyl chlorid formed. The unaltered olefin is passed over calcined aluminium oxid at from 400 to 450 C. in order to isomerize it, and the reaction product is again treated with concentrated aqueous hydrochloric acid in order to remove the trimethyl-ethylene which has been formed. These operations can be repeated as often as necessary.

In order to convert the tertiary isoamyl chlorid (formula I) into dichlor-isopentane,

' that portion of it boiling between 84 and 86 C., is boiled in an apparatus similar to that hereinbefore described and the vapors are mixed with chlorin and subjected to the action of chemically active rays, such as sun light or a uviol lamp, or to the action of a silent electric discharge. Thefldichlorid is obtained in almost quantitative yield and consists chiefly of 2.3-dichlor-2-methylbutane of the formula The same product (namely that of formula XIII) can also be obtained by gradually adding the theoretical quantity of sulfuryl chlorid to pure trimethylethylene, while continually shaking and cooling it so as to ggaiOntain a temperature of from 5 to To convert the said dichlorid into isoprene, it is passed slowly, at a pressure of about 20 millimeters, over heated contact material, such for instance as barium chlorid, at about 350 C. The hydrochloric acid is absorbed by milk of lime and the isoprene is condensed in any suitable manner, for instance by means of a carbon dioxid toluene freezing mixture.

Now what I claim is 1. The process of producing Q-chlor-isopentane by treating a mixture of petrol hydrocarbons consisting chiefiy of normal pentane and isopentane with a chlorinating agent, separating the monochlor derivatives, treating them with an agent adapted to split off hydrochloric acid, acting on the mixture of olefins obtained with hydrochloric acid, separating the 2-chlor-isopentane and acting on the residue with an agent adapted to bring about isomerization, and then acting on the product with hydrochloric acid to obtain more 2-chlor-isopentane.

2. The processof producing 2-chlor-isopentane by treating a mixture of petrol hydrocarbons con.,-isti11g chiefly of normal pentane and isopentane with a chlorinating agent, separating the monochlor derivatives, treating them with an agent adapted to split off hydrochloric acid, acting on the mixture of olefins obtained with hydrochloric acid, separating the 2-chlor-isopentane and acting on the residue with. an agent adapted to bring about isomerization, and then acting on the product with hydrochloric acid to obtain more 2-chlor-isopentane, again separating the 2-chlor-isopentane and repeating the operations of isomerizing, treating with hydrochloric acid and separating until substantially the total quantity of olefins is transformed into 2-chlor-isopentane.

In testi ony whereof I have hereunto set my hand in the presence of two subscribing witnesses. OTTO GRAUL.

Witnesses: Y

J osErH PFEIFFER,

J. Anne. LLOYD. 

